I was wondering about the doughnut on the ackley 40 degree shoulder if it would help to skim the necks before fire forming to the 40 degree shoulder?

Or should I skim the necks after fire forming.

My barrel is not a tight neck. I just wanted to even out the necks a little.

Caliber is 22-250 AI

Thanks in advance

Donuts would not produce any serious problems where the bullet is seated above the donut. It is only when the bullet is seated past the donut that it could cause pressure problems. I would say that if the bullet does not pass the donut, fireform first and then ream the case.

It is allways a good idea to have good quality brass before fire forming, even if it is a standard
case the wall thickness difference will move from the outside to the inside causing a misalignment
of the bullet to the bore.

Only turn what is nessary to clean it up and make all of the cases uniform/consistant.

When wildcatting from one caliber to another ,it is also very important.

Once the case has been fired it cant be trued up as easy, even inside neck reaming is hit
and miss.

To avoid the "Donuts" , all you have to do is seat the bullet long enough to hold the case head against the boltface the first time. Note: reduce the loads to a starting load if seating against
the lands for safety.

I shoot 3 Ackley improved cartridges. I turn necks for 2 of them. The .30-06AI doesn't need it, However I turn necks on the .243 AI when making my brass from .308 Lake City Match brass and I turn it for the 6.5-06AI because I make it out of .270 Win brass and I have a tight throat chamber.

The key for turning it prior to fireforming it to not cut into the shoulder too far as to messs up your head spacing.... All Ackley improved design cases headspace off of this point while fireforming, so leaving enough is important as excessive headspacing will mess up the shoulder, cause casehead separations and other problems.....to find this point, turn the necks until the cutter slightly cuts into the shoulder, check the case in the the chamber and makesure it will still chamber with some slight resistance as it is crush fitting and headspacing.

I then load and fireform and after resizing and cleaning, I check to see if I need to clean up the neck further, as the expanderball seems to push out any doughnut, this takes care of the problem for me.